A wide variety of communication services are available to consumers today. To simplify a user's access to multiple services, communication systems which provide complimentary communication services are being combined and integrated. This allows a consumer to subscribe to one service provider and buy one device which meets many, if not all, of his or her communication needs.
Communication systems, such as "MOTOROLA" "iDEN" systems, provide both interconnect and dispatch communication services. The interconnect services are those traditionally provided by cellular systems and include wireless telephone service, voice mail service, and paging or short message service. The dispatch services are those traditionally provided by two-way radio systems and include group call service, private call service, and call alert service.
The dispatch services allow a user to communicate in ways that are difficult or costly using today's cellular systems. The group call service, for example, enables a user to communicate with a group of people simultaneously and substantially instantaneously. Using a cellular system, such a call could not be established as quickly since either telephone numbers would need to be dialed for a three-way call or arrangements would need to be made to setup a conference call.
Systems that provide both interconnect and dispatch communication services typically have separate controllers, i.e. interconnect controllers and dispatch controllers. The need to minimize development costs and time-to-market makes such a system architecture desirable. However, in a system with independent controllers a user of a service supported by one controller may be unable to contact a user involved in a service supported by the other controller. For example, the group call service, a dispatch service that allows a group of users to communicate, is not able to contact users involved in interconnect services such as telephone calls. The group call must wait for all participants to complete telephone calls in progress or proceed without the participation of some group members.
Likewise, an urgent incoming telephone call is busied while a user completes a dispatch communication in progress. In both cases, a communication service of one type must wait for the completion of a communication service of the other type. In such instances, time is wasted and urgent communications may be delayed.
Again, systems today which provide both interconnect and dispatch communication services have separate controllers. In order to alert a user engaged in one service of another pending service, knowledge of both services is required. When each controller contains knowledge of only one of the services, as is the case when one service is interconnect and the other service is dispatch, such alerting cannot be performed. Therefore, a need exists for an apparatus and method for alerting a communication unit engaged in a communication service supported by one controller of a pending request to participate in a communication service supported by a different controller.